EP1143272A2 - Mechanisch geformte, reversible, optische Glasfasergitter mit langer Periode - Google Patents

Mechanisch geformte, reversible, optische Glasfasergitter mit langer Periode Download PDF

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Publication number
EP1143272A2
EP1143272A2 EP00309572A EP00309572A EP1143272A2 EP 1143272 A2 EP1143272 A2 EP 1143272A2 EP 00309572 A EP00309572 A EP 00309572A EP 00309572 A EP00309572 A EP 00309572A EP 1143272 A2 EP1143272 A2 EP 1143272A2
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EP
European Patent Office
Prior art keywords
grating
pad
fiber
optical
optical fiber
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP00309572A
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English (en)
French (fr)
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EP1143272A3 (de
Inventor
Linn Frederick Mollenauer
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Nokia of America Corp
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Lucent Technologies Inc
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Publication date
Application filed by Lucent Technologies Inc filed Critical Lucent Technologies Inc
Publication of EP1143272A2 publication Critical patent/EP1143272A2/de
Publication of EP1143272A3 publication Critical patent/EP1143272A3/de
Withdrawn legal-status Critical Current

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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G02B6/02057—Optical fibres with cladding with or without a coating comprising gratings
    • G02B6/02071—Mechanically induced gratings, e.g. having microbends
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
    • G02B6/14—Mode converters
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G02B6/02033—Core or cladding made from organic material, e.g. polymeric material

Definitions

  • This invention relates generally to the field of optical communications and in particular to a method and apparatus for imparting long period gratings in an optical fiber.
  • Long-period gratings can be used to provide a phase-matched coupling necessary to transfer power from one mode of an optical fiber to another.
  • the resultant absorption band or resonance is fairly wide, typically >10 nm between the points (henceforth known as the "FWHdB" points) where the logarithm of the loss is half that at the peak.
  • my method for inducing gratings into an optical fiber involves gently pressing the optical fiber into a ruled mechanical grating with a rubber or other elastic pad such that a series of "microbends" are produced.
  • my method is both convenient and produces superior results.
  • gratings constructed according to my method can be long (typically 75-100 mm), and exhibit narrow resonances (typically ⁇ 3 nm between the FWHdB points) suitable for high resolution correction of erbium amplifier gain curves.
  • the fiber used for my method is overcoated with a special low-index (n ⁇ 1.4) plastic, there is no need to strip off the coating thereby preserving the strength and durability of the fibers while at the same time, producing gratings that are exceptionally simple and inexpensive to fabricate.
  • my method also allows one to compensate for random variations in the fiber, which otherwise may produce a small but significant scattering in the resonance wavelengths produced by a particular grating period.
  • a device constructed according to my method is amenable to electro-mechanical control, since the forces and displacements required to induce the gratings are well within the capability of well-known transducers.
  • my invention is directed to the method for producing mechanically induced long period gratings from an optical fiber.
  • my invention is directed to the long period grating mechanically induced into the optical fiber as taught and described herein.
  • apparatus 100 includes an optical fiber 150 interposed between, an overlying plate 110, an underlying plate or substrate 120 which includes a ruled, mechanical grating 140, and one or more fixing/adjustment screws 160.
  • optical fiber 150 becomes "pinched” between the two and becomes deformed where it contacts the ruled grating 140.
  • microbends a mechanically induced, long-period grating is constructed from the optical fiber.
  • any of a variety of known mechanical/electromechanical/piezoelectric adjustment devices may be used. All that is required, is that the device imparts sufficient force to induce the grating into the optical fiber 150 when it is sandwiched between the overlying plate 110 and the underlying plate substrate 120.
  • pad 130 constructed from any of a variety of materials, provides an elastic interface between optical fiber 150 and overlying plate 110.
  • the pad 130 imparts additional "tunability", that is, the ability for a long-period grating constructed according to my teachings to be changed or “tuned” as appropriate to a given application.
  • elastic materials such as rubber, any deformable material may be used although they may not be as reusable or tunable as their more elastic counterparts.
  • Fig. 1A there is shown an exploded, close up view of the pad 130, optical fiber 150, ruled mechanical grating 140 and substrate 120. Shown in this Figure are the microbends 155 of the optical fiber 150 which occur primarily in those regions of the optical fiber 150 which contact the "peaks" and “troughs” of the ruled mechanical grating 140. And while not explicitly shown in this Figure, those skilled in the art will recognize that the pad 130 will likewise deform in areas that correspond to the peaks and troughs of the ruled mechanical grating 140 as the pad 130 and substrate 120/ruled mechanical grating 140 are pressed or urged towards one another, sandwiching the optical fiber 150 between them.
  • FIG. 1 B shows an overhead view of an assembly which imparts mechanically induced long period gratings into optical fiber 150.
  • T ( k, ⁇ ) 1- sin 2 [ kL 1 + ( ⁇ / k ) 2 ] 1+( ⁇ /k) 2 ;
  • Fig. 2 graphically shows T( ⁇ ), for two different values of k.
  • the resonance wavelengths tend to show an almost perfectly linear dependence on the grating period ( ⁇ g ), with a slope of about 2 nm/ ⁇ m, when the latest TRUE WAVE fibers are used.
  • This dependence implies a nearly linear behavior of the quantity k o1 - k cl on . ⁇ .
  • the absolute grating period required for a given resonance wavelength varies from fiber to fiber, however.
  • the grating periods required for a 1550 nm resonance tended to lie closer to 400 ⁇ m than to the values shown in Fig.5. But even within an ostensibly constant fiber type, however, experience shows that both the fiber's diameter and preform irregularities must be tightly controlled in order to have an accurately repeatable relation between resonance wavelength and grating period.
  • ⁇ eff ⁇ g / cos( ⁇ ).
  • Fig. 6 there is shown an example of such angle tuning, where the fiber has been first aligned normally for one pass over the grating grooves, and then at 12.7° to that alignment for the second pass.
  • Fig. 7 By providing for a number of passes of the fiber over a grating at successively increasing angles, one can make a device yielding a uniformly spaced set of resonance wavelengths as shown in Fig. 7.
  • the net loss band can have just about any arbitrary smooth shape, created by adjustment of the strengths of all the individual resonances.
  • Fig. 8 shows an example so produced by 11 gratings, each 75 mm long.
  • pressure bars or steel beams could be employed each containing gratings, of successively increasing period from one bar to the next, in their lower edges. These slender (just a few mm wide), comb-like bars would then press directly into the fiber, which would in turn lie on the rubber pad.
  • This scheme might be especially attractive if the grating bars were reproduced cheaply by molding or stamping from a thermally and mechanically stable plastic material.
  • the energy coupled into the cladding mode must remain with that mode over the length of the grating, it must subsequently be dissipated through bending loss.
  • the fiber outside the grating region is coated with high index plastic, the required loss is obtained in a few centimeters path of slightly bent fiber. With the low index plastic coated fibers, however, much greater length is required to effect the necessary loss. As can be readily appreciated, that is because with the low index coating, the glass cladding remains a fairly good guide, and the cladding mode experiences little loss from the plastic.
  • Fig. 9 there the left hand side of the figure shows the interference fringes obtained from two partially overlapping resonances, when a short (approx 10 cm) loop was used between the two gratings.
  • the interference fringes show that a small but significant fraction of the cladding mode field from the first grating was still present in the region of the second grating.
  • the most serious defect of the resonances is that they tend to suffer a slight polarization-dependent splitting.
  • the origin of this splitting is not known, but one can speculate that it may be related to deviations from perfect cylindrical symmetry, as for example would be produced by an off-center core, or to a mild birefringence induced by the pressure on the fiber, or to a combination of these effects.
  • the splitting in turn results in a polarization-dependent loss (PDL), which is greatest on the sides of the resonance, and typically amounts (in dB) to about 5-10% of the peak dB loss. Although "small”, that amount of PDL is nevertheless intolerable in many applications.
  • Fig. 10 there is shown an example of such a configuration, invoked as an integral part of an erbium fiber amplifier 1000.
  • the amplifier 1000 shown there includes circulator 1020, faraday mirror 1040, pump 1060, erbium-doped fiber 1070 and one or more gratings 1050 constructed according to the present invention.
  • incoming optical signals 1010 are routed by the circulator 1030 through the grating 1050 to the faraday mirror 1040, then passed again through the grating 1050, and amplified through the action of pump 1060 in conjunction with erbium-doped fiber 1070.
  • the amplified optical signals are then output through the action of circulator 1030 as amplified output signals 1020.
  • the PDL is eliminated because of the fact that, due to the Faraday mirror, the polarization state at every point along the return path is exactly orthogonal to the same along the incoming path. Note that this configuration also tends to eliminate any PDL arising from the erbium amplifier fiber itself.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Lasers (AREA)
  • Light Guides In General And Applications Therefor (AREA)
  • Mechanical Light Control Or Optical Switches (AREA)
  • Optical Fibers, Optical Fiber Cores, And Optical Fiber Bundles (AREA)
  • Diffracting Gratings Or Hologram Optical Elements (AREA)
EP00309572A 2000-04-05 2000-10-30 Mechanisch geformte, reversible, optische Glasfasergitter mit langer Periode Withdrawn EP1143272A3 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US09/543,267 US6408117B1 (en) 2000-04-05 2000-04-05 Mechanically induced long period optical fiber gratings
US543267 2000-04-05

Publications (2)

Publication Number Publication Date
EP1143272A2 true EP1143272A2 (de) 2001-10-10
EP1143272A3 EP1143272A3 (de) 2002-01-02

Family

ID=24167279

Family Applications (1)

Application Number Title Priority Date Filing Date
EP00309572A Withdrawn EP1143272A3 (de) 2000-04-05 2000-10-30 Mechanisch geformte, reversible, optische Glasfasergitter mit langer Periode

Country Status (6)

Country Link
US (1) US6408117B1 (de)
EP (1) EP1143272A3 (de)
JP (1) JP2002006141A (de)
KR (1) KR20010098469A (de)
CN (1) CN1316661A (de)
CA (1) CA2336493A1 (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2486460A (en) * 2010-12-15 2012-06-20 Oclaro Technology Ltd Optical fibre attenuator

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US6628861B1 (en) * 1999-01-06 2003-09-30 General Photonics Corporation Control of guided light in waveguide using external adjustable grating
US6542689B1 (en) * 1999-11-15 2003-04-01 Fitel Usa Corp. Attenuator for buffered optical fibers
KR100417467B1 (ko) * 2001-05-04 2004-02-05 송재원 마이크로 밴딩 장주기 광섬유 격자를 이용한 광섬유 증폭기의 파장 가변 이득 평탄화용 필터의 제조 방법
KR100417466B1 (ko) * 2001-05-04 2004-02-05 송재원 마이크로 밴딩 장주기 광섬유 격자의 제조 방법
KR100416452B1 (ko) * 2001-05-10 2004-01-31 학교법인 성균관대학 광섬유격자 가변장치
US6728440B1 (en) * 2001-06-28 2004-04-27 Avanex Corporation Method and apparatus for multi-pass photonic processors with circulators and multiple-fiber collimators
KR100422197B1 (ko) * 2001-07-28 2004-03-11 학교법인 성균관대학 나선형 광섬유격자 제작장치
KR100420940B1 (ko) * 2001-08-03 2004-03-04 학교법인 성균관대학 편광모드 분산방지 광섬유격자 가변장치 및 이의 응용
KR100415713B1 (ko) * 2001-09-07 2004-01-24 학교법인 성균관대학 광섬유격자를 이용한 편광모드분산 보상기
KR20040012359A (ko) * 2002-08-02 2004-02-11 양길호 광섬유를 이용하여 주기적으로 테이퍼 형상으로 제작된 광섬유 증폭기용 이득평탄 필터
KR100477213B1 (ko) * 2002-09-24 2005-03-21 학교법인 성균관대학 광섬유격자 제작 장치
US6950578B1 (en) 2004-05-28 2005-09-27 Fitel Usa Corp. Highly index-sensitive optical devices including long period fiber gratings
US7177510B2 (en) * 2004-08-09 2007-02-13 Fitel Usa Corp. Polarization insensitive microbend fiber gratings and devices using the same
JP2010008900A (ja) * 2008-06-30 2010-01-14 Osaka Prefecture Univ 長周期ファイバグレーティングデバイス
CN101776784B (zh) * 2009-01-13 2011-08-24 电子科技大学 一种2×2长周期光纤光栅耦合器
TW201131221A (en) * 2010-03-15 2011-09-16 Jian-Xian Wu Adjustable fiber grating dispersion compensator
CN102157889A (zh) * 2011-03-21 2011-08-17 山东大学 波长可调谐l波段光纤激光器
TWI457626B (zh) * 2011-12-13 2014-10-21 Nat Univ Chung Cheng Fiber grating sensor
CN102692315B (zh) * 2012-06-19 2015-05-06 南京烽火藤仓光通信有限公司 一种检测光纤微弯损耗的装置及方法
CN105785501A (zh) * 2014-12-24 2016-07-20 Ks光电有限公司 光纤长周期光栅生成装置
CN105739011B (zh) * 2016-05-09 2019-01-08 天津理工大学 一种二硫化钼长周期光纤光栅及其制备方法
KR102121229B1 (ko) * 2018-04-24 2020-06-10 서울시립대학교 산학협력단 장주기 광섬유 격자 및 장주기 광섬유 격자의 제조 방법
CN109814247A (zh) * 2019-03-28 2019-05-28 烽火通信科技股份有限公司 一种光纤传输干扰装置及干扰方法
GB202012809D0 (en) * 2020-07-31 2020-09-30 Corning Inc Polarization controller and method of manufacture

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EP0286350A2 (de) * 1987-04-10 1988-10-12 AT&T Corp. Lichtwellenleiter-Übertragungssystem
US4914665A (en) * 1987-01-20 1990-04-03 Hewlett-Packard Company Broadband-tunable external fiber-cavity laser
US5774619A (en) * 1996-05-15 1998-06-30 Hughes Electronics Corporation Precision deformation mechanism and method
WO1999059010A1 (en) * 1998-05-09 1999-11-18 Korea Advanced Institute Of Science And Technology Fiber grating and fiber optic devices using the same

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GB2058394A (en) * 1979-08-30 1981-04-08 Marconi Co Ltd Pressure-sensitive Optical Fibre Cable
US4477725A (en) * 1981-08-27 1984-10-16 Trw Inc. Microbending of optical fibers for remote force measurement
US4449210A (en) * 1981-12-21 1984-05-15 Hughes Aircraft Company Fiber optic hydrophone transducers
US4749246A (en) * 1984-03-06 1988-06-07 Stc Plc Optical fiber sensors
GB2188719A (en) * 1986-04-02 1987-10-07 Stc Plc Optical fibres
US4914665A (en) * 1987-01-20 1990-04-03 Hewlett-Packard Company Broadband-tunable external fiber-cavity laser
EP0286350A2 (de) * 1987-04-10 1988-10-12 AT&T Corp. Lichtwellenleiter-Übertragungssystem
US5774619A (en) * 1996-05-15 1998-06-30 Hughes Electronics Corporation Precision deformation mechanism and method
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Publication number Priority date Publication date Assignee Title
GB2486460A (en) * 2010-12-15 2012-06-20 Oclaro Technology Ltd Optical fibre attenuator

Also Published As

Publication number Publication date
JP2002006141A (ja) 2002-01-09
CA2336493A1 (en) 2001-10-05
EP1143272A3 (de) 2002-01-02
KR20010098469A (ko) 2001-11-08
CN1316661A (zh) 2001-10-10
US6408117B1 (en) 2002-06-18

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